pub fn new_count_distinct(input_str: &str) -> usize {
    //记录已经出现的串，检查当前串是否已经出现
    let mut result : usize = 0; //记录结果
    let str : Vec<&str> = input_str.split(",").collect();
    let mut out : Vec<&str> = Vec::new();   //已经出现的串
    for s in str {
        if  out.clone().into_iter().find(|&x| x == s) == None {
            out.push(s);
            result = result + 1;
        }
    }
    result
}
